Lack of awareness key barrier to breast cancer chemoprophylaxis

Tamoxifen is well-known for its role as part of adjuvant treatment for breast cancer.
 
But the fact it can also reduce breast cancer risk by one-third to one-half in women at high risk of the disease is less commonly known, with new research finding 35% of GPs are unaware of the availability of preventive medicine for breast cancer.
 
For the study, more than 720 Australian women and 220 of their clinicians responded to a survey assessing awareness of preventive medications that can reduce the risk of breast cancer.
 
The study found that only 10 of the women (1.4%) had ever taken preventive medication, with half the respondents (52%) unaware this was an option.
 
Co-author Professor Jon Emery, GP and Herman Professor of Primary Care Cancer Research at the University of Melbourne and Western Health, told newsGP he was not surprised by these findings.
 
He says there have been Australian guidelines since 2010 recommending chemoprevention be considered an option for women at increased risk of breast cancer, but it is not common knowledge among clinicians.
 
‘The RACGP Red Book was updated to include this recommendation, but there have been no efforts to implement these guidelines,’ he said.
 
Professor Emery says uptake of such medications for this purpose is ‘low’, even though tamoxifen is listed on the Pharmaceutical Benefits Scheme (PBS) for this indication. Even when clinicians are aware of the benefits of chemoprophylactic agents, he is concerned they are still under-prescribed out of fear of side effects and risks.
 
‘I think few GPs would be willing to commence tamoxifen or raloxifene,’ Professor Emery said.
 
He says concerns regarding potential side effects are ‘entirely reasonable’.
 
‘But our study showed [GPs] would be prepared to provide ongoing prescriptions once initiated by a hospital specialist,’ he said.
 
Lead researcher Dr Courtney Macdonald says the risks of tamoxifen as a preventive medication is often overstated.
 
‘When taken preventively, tamoxifen is generally well-tolerated and side effects tend to be overestimated by women and doctors,’ she said.
 
Of the patients who were aware of the availability of chemoprophylaxis, the study found 31% were concerned about side effects and 23% cited inadequate information as the main reason they did not take preventive medicine.

Professor Jon Emery says chemoprophylaxis is still seen as a ‘new area’ of medicine.

While clinicians play a key role in informing patients about preventive medication, Professor Emery says women can also utilise the risk tool iPrevent to help them determine whether chemoprevention may assist in the management of their breast cancer risk.
 
Professor Emery understands the hesitation regarding prescribing chemoprophylaxis in general practice.
 
‘This is still seen as a new area of medicine, the idea of prescribing drugs to reduce risk of cancer,’ he said.
 
A ‘lack of tools’ to support discussions in general practice is another issue that needs to be addressed. However, Professor Emery says that if a patient is deemed at risk of breast cancer and a GP is reluctant to initiate chemoprevention, such women can be referred to a breast surgeon or a familial cancer service.
 
Dr Victor G Vogel, National Vice President of Research for the American Cancer Society, also voiced his concern about this issue in a response to the original research, published in Cancer Prevention Research.
 
Despite ‘strong evidence’ chemoprophylaxis is efficacious, Dr Vogel believes it remains underused in eligible women.
 
He says this new research is a reminder that the problem of lack of uptake of risk-reducing medications for breast cancer remains a ‘worldwide clinical challenge’, despite endorsements from national and international organisations that recommend the use of such medications with level I evidence.
 
According to Cancer Australia, the most commonly used risk-reducing medications for women at high risk of breast cancer are tamoxifen and raloxifene – both selective oestrogen receptor modulators (SERMS).
 
Professor Emery says aromatase inhibitors such as anastrazole can also be used for chemoprevention for breast cancer in certain cohorts and can also reduce the risk of breast cancer by one-third to one-half.
 
Cancer Australia indicates tamoxifen and raloxifene aim to reduce a woman’s risk of developing oestrogen receptor-positive (ER+) invasive breast cancer by interfering with the actions of oestrogen on breast tissue.
 
Such medications may be considered in women with an increased risk of breast cancer, based on family history, though there is limited evidence about the effect on women with the mutation BRCA1 or BRCA2 genes.
 
The decision to use tamoxifen or raloxifene for a post-menopausal woman should be guided by an assessment of each woman’s individual needs and existing comorbidities, including osteoporosis.
 
While there are factors that need to be taken into account before prescribing chemoprophylaxis, Professor Emery is concerned that failing to address this issue means women at increased risk of breast cancer may miss out on important measures that may reduce their risk of disease.
 
‘Some women at increased risk of breast cancer may want to consider this as part of the management of their risk, as well as additional breast cancer screening,’ he said.
 
‘GPs are key to identifying women at increased risk and being aware this is an evidence-based option.’
 
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breast cancer chemoprevention preventive medicine tamoxifen